Browsing by Author "Medina, Jean"

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    Comparison between poly(azomethine)s and poly(p-phenylvinylene)s containing a di-R-diphenylsilane (R = methyl or phenyl) moiety. Optical, electronic and thermal properties
    (2021) Sobarzo, Patricio A.; Mariman, Andrea P.; Sanchez, Christian O.; Hauyon, Rene A.; Rodriguez-Gonzalez, Fidel E.; Medina, Jean; Jessop, Ignacio A.; Recabarren-Gajardo, Gonzalo; Tundidor-Camba, Alain; Terraza, Claudio A.
    Two new silicon-containing poly(azomethine)s (PAzM-Me and PAzM-Ph) and two new silicon-containing poly(pphenylvinylene)s (PPVSi-Me and PPVSi-Ph) were obtained from 4',4'''-(dimethylsilanediyl)bis([1,1 '-biphenyl]-4-carbaldehyde) and 4',4'''-(diphenyl silanediyl)bis([1,1 '-biphenyl]-4-carbaldehyde) with p-phenylendiamine for PAzMs or phenylenebis(methylene))bis(triphenylphosphonium) bromide for PPVSis. All polymers were structurally characterized by FT-IR, NMR and elemental analysis. The materials showed a high thermal stability (501-538 degrees C) with the TPS-core increasing this parameter. The absorption and emission of PAzMs and PPVSis were closely related with the nature of the silane-core in the backbone. All samples showed wide-band gaps where the TPS-core-based materials evidenced the lower energy transitions; PAzM-Ph (2.83 eV) and PPVSi-Ph (2.81 eV). This work lay the groundwork for new architectures of silane-based poly(azomethine)s and poly(p- phenylvinylene)s derivatives for potential optoelectronic applications.
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    Synthesis of dimethyl- and diphenylsilane-based oligo(azine)s: Thermal, optical, electronic, and morphological properties
    (2022) Sobarzo, Patricio A.; Jessop, Ignacio A.; Perez, Yasmin; Hauyon, Rene A.; Velazquez-Tundidor, Maria V.; Medina, Jean; Gonzalez, Alexis; Garcia, Luis E.; Gonzalez-Henriquez, Carmen M.; Coll, Deysma; Ortiz, Pablo A.; Tundidor-Camba, Alain; Terraza, Claudio A.
    Four new oligo(azine)s were synthesized from dimethyldiphenylsilane and tetraphenylsilane core-based dialdehydes and hydrazine by high-temperature polycondesation and proposed as materials for optoelectronic applications. The oligo(azine)s were characterized by EA, FT-IR, and NMR. Although most of samples were poorly soluble, TPS-containing PAZ-4 was soluble in aprotic polar solvents. According to SEC and FT-IR studies, the samples were oligomers with up to five repeating units long. TGA showed highly stable samples with TDT10% over 420 degrees C except for PAZ-1 that contains a DMS core along with phenyl units, and thus, the lowest carbon content in the series. From DSC analysis, the substitution of phenyl groups in PAZ-1/3 by biphenyl moieties in PAZ-2/4 allowed to obtain oligo(azine)s with lower T-g values. PAZ-4 showed a UV-A absorption with optical band-gap values of 2.91 and 2.65 eV from UV-vis (solution) and DRS (films), respectively. PL analysis showed a violet emission. PAZ-4 showed resistivity of 29.24 omega cm, similar to wide-band gap materials. Their contact angle measurements showed a critical surface tension of 42.29 dynes/cm, revealing its hydrophobicity. AFM analysis indicated that the PAZ-4 films had homogeneous surfaces. Young's modulus close to 4.46 GPa was established by microindentation for the PAZ-4 thin-films.
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    Tetraphenylsilane-based oligo(azomethine)s containing 3,4-ethylenedioxy- thiophene units along their backbone: Optical, electronic, thermal properties and computational simulations
    (2022) Sobarzo, Patricio A.; Gonzalez, Alexis; Jessop, Ignacio A.; Hauyon, Rene A.; Medina, Jean; Garcia, Luis E.; Zarate, Ximena; Gonzalez-Henriquez, Carmen; Schott, Eduardo; Tundidor-Camba, Alain; Terraza, Claudio A.
    A series of three new oligo-poly(azomethine)s (o-PAzMs) were successfully synthesized, incorporating tetra-phenylsilane (TPS) and 3,4-ethylenedioxythiophene (EDOT) moieties with Mn and Mw between 3.9 and 5.4 kDa and 8.3-11.6 kDa, respectively. The silylated o-PAzMs were highly soluble in low-boiling point solvents such as CHCl3, THF, and CH2Cl2. All three materials are highly thermally stable, with onset temperatures of degradation of at least 250 degrees C and with TDT10% between 340 and 460 degrees C. The glass transition temperature values agree with the flexibility of the repetitive units and showed values between 125 and 155 degrees C. The absorption and emission of the o-PAzMs were observed in the blue-violet UV-vis region (350-550 nm) with moderate Stokes shifts (48-71 nm). The oligomers are it-conjugated wide-band gap materials (2.83-2.73 eV), where the high electronic tran-sitions would be associated with disruption of it-conjugation, which is promoted by the TPS core and (d-p)it orbital interactions. This disruption controls the effect from the EDOT unit rich donor on HOMO (-5.79 eV to-5.71 eV) and LUMO (-2.98 eV to-2.89 eV) energy values. Furthermore, DFT and TDDFT calculations were performed to theoretically characterize the observed UV-Vis transitions and frontier molecular orbitals (MOs) energies.